Solvent-free synthesis of 1,8-Dioxo-octahydroxanthenes and 14-Aryl-14 H -dibenzo[ a,j ]xanthenes using saccharin sulfonic acid as an efficient and green catalyst

Saccharin sulfonic acid (sasa) is utilized as a highly efficient,green and inexpensive sulfonic acid-containing catalyst for the following one-pot multi-component organic transformations: (i) the condensation of dimedone (2 eq.) with aromatic aldehydes (1 eq.) leading to 1,8-dioxo-octahydroxanthenes,and (ii) the reaction of 2-naphthol (2 eq.) with arylaldehydes (1 eq.) leading to 14-aryl-14h-dibenzo[a,j]xanthenes. in these protocols,the title compounds are produced in high to excellent yields and in relatively short reaction times under solvent-free conditions. © 2012 hindawi publishing corporation.